For electrographic printers, a method is well know by which the image is formed by each process of charging, exposure, development, transfer, fusion and cleaning. Of these, for the development process, a contact type development device, in which a development roller contacts to a photosensitive drum and which applies a voltage to the development roller and uses non-magnetic monocomponent toner to develop an electrostatic latent image on the photosensitive drum, is widely used for advantages of miniaturization and low cost.
In such a conventional development device, it is common that a supply roller is pressed against the development roller. However, there are demands to reduce a drive torque and to suppress heat in order to realize, for example, a speed printing. As a method to reduce the drive torque, a development device in which the development roller and the supply roller provided with projections (large surface roughness) are arranged in a non-contact manner (for example, see Japanese Laid-Open Patent Application Publication No. H02-101485 (page 2, left lower column, line 14—page 5, right upper column, line 1, and FIGS. 1 and 8).